Glass fabric having improved yarn slippage and hand



United States US. Cl. 260-29.6 7 Claims ABSTRACT OF THE DISCLOSURE A liquid treatment for fibers, and particularly glass fibers, which provides improved hand and high retention of the strands against edgewise removal.

The present invention relates to a coating material for glass fibers which will produce a durable smooth finish and will flexibly bond adjacent fibers together; and to glass fibers and woven glass fabrics so coated.

Prior to the present invention, it has not been possible to produce flexible glass fabrics whose fibers could not easily be pulled from a cut edge. The art commonly calls endwise removal of fibers from a cut edge yarn slippage. Yarn slippage is measured by an ASTM test procedure D434-42. According to this test procedure, a 4 x4" piece of glass fabric to be tested is sewn onto a 4" x 8" piece of the woven fabric using fourteen stitches to the inch, and the force required to pull the piece of cotton fabric from the fabric being tested using a Scott Tester is recorded in pounds and is directly proportional to the force required to remove the fibers endwise from the fabric. The greater the numerical value of yarn slippage, the stronger the fabric. The hand of the fabric is a term used to describe the flexibility of the fabric and is arbitrarily determined by wadding the fabric up in a persons'hand. The ease by which the wadding takes place is termed the hand of the fabric, and the softer or more flexible the fabric, the better the hand. A coating which cracks during the wadding process, is unacceptable for textile uses.

Prior to the present invention, there were no finished coatings for glass fibers which would produce a fabric of' acceptable hand comparable to that of cottons, woolens, and the like, and which would have a high numerical value of yarn slippage. I-Ieretofore, resin binder finishes which would bind smooth glass fibers together in a manner providing high yarn slippage were too stifi to provide good hand. Conversely, binder coatings which were sufliciently flexible to provide a good hand for glass fabrics were not sufiiciently strong to give high numerical values of yarn slippage. The problem has been a difiicult one and has prevented glass fabric from being used in many textile applications, as for example blankets, wearing apparel, and other materials which are washed frequently. In addition to withstanding the flexing and abrading that occurs during washing operations, the finished coating must be Water insoluble, it must prevent the water from penetrating to the surface of the glass, and it must in most cases be capable of fixing organic and/ or inorganic dye stuffs so that they will not be removed during washing.

An object of the present invention is the provision of a new and improved finish coating for glass fabrics which will provide high yarn slippage and good hand.

A further object of the invention is the provision of a new and improved coating for glass fabrics which will provide high yarn slippage, good hand, and which coating will not be removed by repeated machine washings using water and detergent.

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A further object of the invention is the provision of a new and improved finished coating material of the above described type which will permanently fix organic and/ or inorganic pigments or dyes to glass fabric.

Further objects and advantages of the invention will become apparent to those skilled in the art to which it relates from the following description of the structure produced by the invention as well as preferred embodiments, and the manner in which these embodiments are made.

The finished coatings which have been used heretofore have generally been polymeric materials which have been polymerized in situ to provide a generally impervious resin coating bonded to the glass fibers. These coatings have sometimes been laid down from organic solution while others have been laid down from water emulsions. In either instance, suflicient polymerization has taken place to provide a stiff polymer layer. Some of these films have depended upon continuity about the glass fibers for affecting a bond to the fibers, while others have used bonding agents such as organosilanes or organo metal complexes to chemically attach the coatings to the surface of the glass fibers.

It has now been discovered that it is possible to produce an impervious coating having good hand and yarn slippage, as well as all of the other necessary properties of a good textile finish, by a structure wherein particles of a resin are mechanically interlocked in a film with some of the interlocking particles being connected to one glass fiber while others are connected to an adjacent glass fiber. Weak secondary forces bond the particles of the resin together to provide an impervious finish layer while permitting a relative fiexure of the particles, and chemical bonds bind the particles to the glass. Because the particles are interlocked, relatively high tensile strength is produced; and because the particles are not bound together by strong primary chemical bonds, the film has good flexibility.

A desirable interlocking of the resin particles is achieved by chemically bonding one functional group of a water soluble bi-functional molecule to a particulate matter supported as a water emulsion or dispersion, and bonding the other fiunctional group of the molecules to the surface of the glass. Upon removal of the water, the resin particles become mechanically knit together, and because of their hydrophobic nature will generally exclude water. While some cross-linking of these particles of polymer may take place, secondary forces such as Van der Waal forces will hold the film together to produce a very flexible yet strong film. Where increased stiffness is desired, particles of a polymer having some remaining reactive groups can be used to provide a small amount of chemical cross-linking between the particles at locations where they are brought together during the removal of the water. This cross-linking, ofcourse, will not be complete so that relative rotation of these particles can still take place. The structure can be likened to a plurality of interlocking balls which are free to rotate relative to each other and are sufficiently close to each other to prevent an inside layer of the balls from being pulled outwardly of an outer layer of the balls. Molecular handles of suflicient length, extend between the outer balls to attach the inside balls to a glass surface outwardly of the outer balls.

The invention is best exemplified by the following preferred embodiment.

Example 1 A textile fabric of glass fibers is heat cleaned to remove any previous size and is then immersed for five minutes in a water system containing approximately 12 percent by weight of the following mixture of ingredients.

Aridye Padding N Colors 2 "Polycryl 7Fl2 is a trade name of Polymer Industries, Inc. for an emulsion of a polyaorylic acid polymer having substantially no remaining active groups except carboxyl groups. Polycryl 7Fl0 is a trade name of Polymer Industries, Inc. for an emulsion of an acrylic material containing an acrylic copolymer polymerized to a high molecular weight material having some amine and car-boxyl groups remaining. Syl-Soft 16 is a trade name of Dow Corning Corp. for a copolymer of methyl hydrogen silicone and dimethyl silicone having some labile hydrogen remaining. Aridye Padding N Colors are made by Inter-chemical Corporation. The water soluble epoxy is a material produced in accordance with US. application, Ser. No. 213,133, filed July 30, 1962 and continuation-in-part Ser. No. 540,532, filed Apr. 6, 1966, now US. Patent 3,336,253. This material has a substituted ammonium ion at one end of a molecular chain with an oxirane group spaced therefrom by more than approximately ten atoms. The epoxy material before reaction with the amine had the following formula:

H H H OH: H H H H- oC Oo H I I Some lower polymers of the above molecule were also present in the material.

A hundred pound mix of the material is prepared by mixing 0.05 pound of glacial acetic acid to 1.0 pound of the epoxy material dissolved in diacetone alcohol followed by the addition of two pounds of warm water added slowly while stirring until the epoxy material goes intosolution. This material is put into a mix tank containing pounds of water, and the alkyl hydrogen silicone (Syl-Soft 16) is added thereto and thoroughly mixed. Thereafter, emulsions of the polyacrylates (Polycryl 7F12 and Polycryl 7Fl0) are added with stirring. The dye stuif is added and thereafter suflicient water is added to make a hundred pounds of the mix. In those instances where an anionic dye stuff is used, the pH is first raised to 8 with ammonium hydroxide. A fabric weighting 4.76 ounces per square yard having a warp of 60 yarns per inch. and a fill of 58 yarns per inch when immersed in the above material and dried at 350 F. will have a coating comprising between 1 /2 to 2% by weight of the finished cloth as determined by ignition loss and will have an ASTM yarn slippage value of from 30 to 35 pounds. This material will withstand ten machine washings without apparent loss of color.

The water soluble epoxy prepolymer used in the above example is a long chain molecule having two functional groups separated by a chain of at least ten atoms. As explained in the application, Ser. No. 213,133, long chain otherwise insoluble molecules, whether or not they include oxirane groups, can be water solublized by a substituted ammonium ion having OH groups in proximity thereto. The combination of the OH group and the ammonium ion in combination produces a very strong solublizing afi'ect. In the materials taught by application Ser. No. 213,133, the OH groups are atttached to the beta carbon relative to the nitrogen atom, and this OH group provides one functional group of the difunctional solubilized molecule. Where the solubilized molecule is an epoxy, it will, of course, have an oxirane group as the other functional group, and this is located in the chain more than ten atoms away from the OH group.

In general the hydrogen of a primary or secondary amine is more reactive than an OH group on a carbon atom, and an OH group is more reactive than a carboxyl group. In the particular materials of the above identified application the OH group is believed to be selectively reacted with the hydrolyzed hydrogen site of the silicon atom of the organo-siloxane because the ammonium ion adjacent thereto is cationic, and this charge phenomenon draws this end of the molecule toward the hydrolyzed silicon atom. The reaction between the OH group and the hydroxyl site of the silicon atom to form a C--OSi bond can proceed either immediately or over a period of time depending upon temperature, because the molecules are held in an oriented position. When the polyacrylic polymers are added to the mixture, the oxirane groups are therefore in the vicinity of the carboxyl groups of the polyacrylic acid, and a reaction there between takes place when the coated fabrics are dried at approximately 350 F.

The Polycryl 7F12 material used in the above example is a polymer of medium molecular weight whose remaining reactive groups consist principally of carboxyl groups. While this material can be linked to other functional groups, such as the oxirane group of the water soluble molecules used in Example 1, it will generally be desired to produce a stronger bond relative to the water soluble molecules. This can be conveniently accomplished by using a polyacrylic acid containing additional, more reactive groups, such as amine groups. The Polycryl 7Fl0 is such a material and will cross link more easily and quickly to the water soluble molecules during the time that the water is being evaporated, and during the time that the film on the fabric is shrinking together. It has been found, however, that the use of the more reactive 7F10 by itself produces too much cross linking between the polymer particles. By disbursing the more reactive 7F 10 particles among 7F12 particles the cross linking of these particles is greatly reduced without decreasing the strength of its chemical bonds to the long chain water soluble molecules. Because the water soluble molecules of Example 1 have different functional groups at its opposite ends, only one functional group of each molecule is caused to react with the organo-siloxanes, and substantially no cross linking is produced at this time. Thereafter the other functional group, which is less reactive, can be caused to react selectively with the later applied particles.

After the molecules have been linked up in the selective manner above described, a dye stuff is added which will react with remaining functional groups, or as in the case of inorganic pigments, is mechanically bound during the shrinkage that takes place during the drying and curing stage. These dye stuffs can be non-ionic or cationic in nature, and if the bath into which the fabric is dipped is caused to have a pH greater than approximately 8, as produced by the addition of ammonium hydroxide and the like, an anionic dye can be used. The dyes which can be used, although not limited to, may include: nitroso pigments such as Naphthol Green B; nitro pigments such as Naphthol Yellow S, Pigment Chlorine GG and Lithol Fast Yellow GG; azo pigments such as Toluidene red, para reds, hansa yellows, permanent orange, benzidene yellows, Persian orange and Lithol red; pyrazolone pigments such as Hausa Yellow R; basic dye pigments such as Malachite Green, Crystal Violet, Auromine O, Auromine G, Setoglaucine, Brilliant Green, Magenta, Methyl Violet, Rhodamine B, Thiofiavin T, Methylene Blue; auxanthine dye pigments, anthroquinone pigments, vat color pigments and phthalocyanine pigments such as indigo, Ciba Violet, Algal Yellow, Monastral Blue, Syrian Blue and the like.

After a film of the material given in Example 1 has been formed, it may be desirable in some instances, although not necessary, to apply a water proofing, and/or a material which will aid in fixing some of the dye stuffs, as is well known in the art. In some instances, it may be desirable to apply a 2 to 2.5% solution of Quilon which is a chromium organo complex commonly used as a final water proofing treatment.

The flexible type of structure above described is pro duced by reason of the type of bond structure and arrangement of the molecules, substantially independently of the proportions of the various ingredients. Not all proportions, however, will provide an acceptable surface for glass fibrics, and the following tabulation will generally give the proportions necessary to provide useful finish coatings for glass fabrics.

Ingredients: Percent by weight Soluble epoxy prepolymer 0.5 to 20 Acetic acid .01 to 1 Syl-soft 16 5 to 50 Polycryl 7Fl2 Polycryl 7F10 5 20 Dispersed pigment dyestuif 0 to Example 2 A material is prepared in the same manner as given in Example 1 above excepting that a water soluble molecule having the following formula is used in place of the water soluble epoxy of Example 1:

where (OR) is a polyglycol of ethylene glycol having a molecular weight of approximately 400.

This material was mixed in the same manner and had generally the same properties when applied to a glass fabric as did the material of Example 1. Similar materials having (OR) groups with over 1,000 molecular weight have been used successfully. It will be noted that the material of Example 2 is generally the same as that of Example 1 except that a polyglycol has been reacted with the oxirane group. This provides a reactive OH group adjacent the ether linkage produced by the reaction, as well as at the end of the molecule. It will now be apparent that any water soluble molecule having two functional groups separated by a chain length of approximately 10 atoms can be used. Such materials will include the polyglycols, such as the carbowaxes, straight-chain noncross-linked polyesters, straight-chain noncrosslinked polyamines, etc. Preferred materials are had when the spaced apart functional groups of the above materials have different reactivity.

While polyacrylic materials are a preferred particulate material, because of the smooth hard surface which they produce on fabric, it will be apparent that any polymer which has been polymerized to a state producing particles of the size which can be supported as a water emulsion will be suitable, provided they still contain some functional groups for bonding with one end of the water soluble molecules. These particles will include polyesters, polyamides such as the nylons when polymerized to a generally noncrosslinking state, phenol formaldehyde resins, and in particular novolac resins, ureaformaldehyde resins, melamine formaldehyde resins, epoxy polymers, polyurethane polymers, etc.

The organo-siloxanes which are used can be any siloxane polymer that includes labile hydrogen attached to the silicon atoms throughout the molecule, and which molecule is not substantially crosslinked, but is in a linear state.

It has further been found that the coating compositions of the present invention provide improved finishes on fabrics other than glass fabrics, as for example, cotton, woolens, polyesters, nylons, and other synthetic fibers.

While the invention has been described in considerable detail, we do not wish to be limited to the particular embodiments described; and it is our intention to cover hereby, all novel adaptations, modifications, and arrangements thereof which come within the practice of those skilled in the art to which the invention relates and which come within the following claims.

We claim:

1. A aqueous coating material for glass, cotton, woolen, polyester, and nylon fabrics and the like made by mixing the following nonaqueous ingredients in the following approximate weight percentages in the presence of water: 550% of an organosiloxane polymer having labile hydrogen on the silicon atoms, 05-20% of water soluble difunctional epoxy containing molecules having a first functional group adjacent one end and separated from a second functional group by more than approximately 10 atoms, said first group being a substituted ammonium radical formed from an alkanol amine, and said second functional group being an oxirane group, 5-20% of particulate prepolymers of acrylic acid containing reactive amine groups, and 0-10% pigment.

2. The coating material of claim 1 wherein the first functional group is an acidified reaction product of an oxirane group and diethanol amine.

3. The coating material of claim 2 having approximately 2% by weight of a dispersed pigment dyestuff therein.

4. The coating material of claim 2 wherein the particulate prepolymers are added to an aqueous solution of the or-ganosiloxane and water soluble difunctional molecules.

5. Glass fibers having a coating thereon deposited in situ from a water emulsion of the following ingredients wherein the nonaqueous ingredients consist essentially of the following percentages by weight:

05-20% of a water soluble epoxy prepolymer having a single terminal group which is the acidified reaction product of an oxirane ring and an alkanol amine having an amine hydrogen thereon,

5-50% of an organosiloxane polymer having labile hydrogen on the silicon atoms,

520% of acrylic resin particles containing reactive amine groups, and

0l0% of a dispersed pigment dyestuif.

6. The glass fibers of claim 5 wherein the coating is deposited from materials consisting essentially of the following approximate proportions by weight:

1.0 of the water soluble epoxy, 10.0 organosiloxane polymer, and

12.0 of the acrylic resin.

7. The glass fibers of claim 6 wherein the soluble epoxy is the reaction product of an epoxy having a molecular chain corresponding generally to the following structure:

IIIH

0 and lower polymers thereof.

References Cited MURRAY TILLMAN, Primary Examiner. H. ROBERTS, Assistant Examiner.

US. Cl. X.R. 117-126, 138.8, 141, 161 

